CN101458940B - Objective lens and optical information recording/reproducing device having the same - Google Patents
Objective lens and optical information recording/reproducing device having the same Download PDFInfo
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- CN101458940B CN101458940B CN200810185762.8A CN200810185762A CN101458940B CN 101458940 B CN101458940 B CN 101458940B CN 200810185762 A CN200810185762 A CN 200810185762A CN 101458940 B CN101458940 B CN 101458940B
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- light beam
- object lens
- step group
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1392—Means for controlling the beam wavefront, e.g. for correction of aberration
- G11B7/13922—Means for controlling the beam wavefront, e.g. for correction of aberration passive
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1374—Objective lenses
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
- G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0908—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only
Abstract
There is provided an objective lens for information recording/reproducing for three types of optical discs, which includes a first area contributing to converging a third light beam onto a record surface of a third optical disc. The first area includes a phase shift structure having refractive surface zones concentrically formed about a predetermined axis. The phase shift structure includes first and second step groups. The first step group is configured such that an optical path length difference DeltaOPD1 (nm) given by each step of the first step group to a first light beam satisfies a condition: 2N1+1.10<|DeltaOPD1/lambda1|<2N1+1.40, where N1 is an integer or zero, and the second step group is configured such that an optical path length difference DeltaOPD2 (nm) given by each step of the second step group to the first light beam satisfies a condition: 2N2-0.10<|DeltaOPD2/lambda1|<2N2+0.10, where N2 is an integer.
Description
Technical field
The present invention relates to a kind of object lens that are installed in optical information recorder/transcriber, this optical information recorder/transcriber is used on the different polytype CD of recording density recorded information and/or information reproduction from it.
Background technology
Have multiple compact disk standards (CD, DVD etc.) now, they are different at aspects such as recording density, protective layer thickness.Simultaneously, in order to obtain higher information storage capacity, the new standard CD (HD DVD, i.e. high definition DVD, BD, i.e. Blu-ray Disc etc.) that will have the recording density higher than DVD in recent years drops into actual the use.The protective layer thickness of this new standard CD is equal to or less than the protective layer thickness of DVD in fact.Use the CD of multiple standards for the ease of the user, require optical disc information data recording/reproducing device (more specifically, be installed in this device objective lens optical system) in recent years that above three types CD is had compatibility.Additional disclosure, in this manual, " optical information recorder/transcriber " comprises the device that is used for information regeneration and information record, the device that only is used for the device of information regeneration and only records for information.Above-mentioned " compatibility " even mean when switching the CD that is using, optical information recorder/transcriber does not need to change assembly yet, just can guarantee information reproduce and/or the information record.
In order to provide a kind of CD to multiple standards to have compatible optical information recorder/transcriber; the NA (numerical aperture) that this device must be configured to objective lens optical system that can be by change being used for information regeneration/record form the bundle spot of the specific recording density of the CD that is suitable for using, and the while can also be proofreaied and correct the spherical aberration that the protective layer thickness that changes according to the switching between the CD of various criterion changes.Because when the wavelength of light beam shortens, the diameter of bundle spot also can diminish usually, so optical information recorder/playback system uses the multiple laser bundle with different wave length selectively according to the recording density of the CD that is using.For example, DVD is used the laser beam of the about 660nm of wavelength, the wavelength of the about 790nm that uses than CD is lacked.For above-mentioned new standard CD, use the used shorter laser beam (for example so-called " blue light " is about 408nm) of wavelength of wavelength ratio DVD, in order to handle the superelevation recording density.
In recent years, have a kind of technology to be put into actual use, this technology arranges the annulus structure by at least one optical element (for example object lens) to objective lens optical system, light beam is suitably converged on the recording surface of the CD that is using.More specifically, the annulus structure that forms at optical element surface is configured to have a plurality of annuluses that are divided into by small step.By the effect of annulus structure, will have each bundle in polytype light beam of different wave length and suitably converge on each the recording surface in the CD of various criterion.
Preferred above-mentioned optical element has the wavelength of the laser beam that correction ought use because the function of the spherical aberration of generation when for example temperature variation be offset from design wavelength of the individual difference XOR environmental change between the light source.Term " design wavelength " mean in the CD of various criterion each record and/or the optimal wavelength of reproduction.
Jap.P. discloses the CD (for example CD, DVD and HD-DVD) that discloses among the NO.2007-4962A (being called JP2007-4962A hereinafter) three types temporarily and has the example of compatible objective lens optical system.Disclosed objective lens optical system has phase-shift structure among the JP2007-4962A, and this phase-shift structure is designed to using the new standard CD for example to realize high light utilization efficiency in the HD-DVD.In addition, objective lens optical system is configured to prevent that by the longitudinal chromatic aberration in the control CD use signal to noise ratio (S/N ratio) of the focus error signal that the unexpected order of diffraction light (that is, veiling glare, flare light) in the CD use causes from reducing.In this manual, term " light utilization efficiency " means the ratio of the amount of the light that the light quantity on the recording surface that is limited at the CD that is using sends about light source.
Term " unexpected order of diffraction light " means the light of the order of diffraction that is not used in information record and information regeneration.On the other hand, " normal order of diffraction light " means the light for the order of diffraction of information record and information regeneration.
Needn't be that cost is brought up to quite high level with the light utilization efficiency of new standard CD with the light utilization efficiency of the CD of other types.The objective lens optical system that in other words, can have compatibility based on the design concept design different with JP2007-4962A to three types CD (for example CD, DVD and new standard CD).For example, in order to guarantee that the designer can improve the light utilization efficiency of CD to a certain extent be used to the CD with relatively low recording density for example writing function of CD or the stability of representational role.
But the light utilization efficiency that improves CD causes the reduction of the signal to noise ratio (S/N ratio) of the appearance of unexpected order of diffraction light in the use of new standard CD and focus error signal.Identical with the situation of disclosed objective lens optical system among the JP2007-4962A, can prevent that the signal to noise ratio (S/N ratio) of focus error signal from reducing by the convergent point of the unexpected order of diffraction light of fine setting.But it should be noted that the new standard CD can have the sandwich construction that is made of several record layers.Therefore, iff based on the design concept of JP2007-4962A design objective lens optical system, unexpected order of diffraction light may converge on the recording layer that the recording layer assembled with normal order of diffraction light approaches.In this case, may have a strong impact on focus error signal.
Summary of the invention
The invention has the advantages that provide in object lens and the optical information recorder/transcriber one of at least, it can have compatibility by the CD to polytype various criterion by forming suitable bundle spot at the recording surface of each CD, simultaneously can suppress spherical aberration, can also improve the light utilization efficiency of the CD (for example CD) with relatively low recording density, even and when using the CD with high record density for example HD DVD the time, also longitudinal chromatic aberration can be suitably suppressed, the signal to noise ratio (S/N ratio) of focus error signal high level can be remained on simultaneously.
According to an aspect of the present invention, provide a kind of object lens for optical information recorder/transcriber, this optical information recorder/transcriber is used for comprising having first wavelength X by optionally using
1(nm) first light beam, has second wavelength X
2(nm) second light beam and have a wavelength lambda
3(nm) one of light beam of three types of the 3rd light beam, recorded information and/or information reproduction from it on three types the CD.At least three types CD comprises that use first light beam carries out second CD of information record or information regeneration and uses the 3rd light beam that it is carried out the 3rd CD of information record or information regeneration it first CD, use second light beam that it carries out information record or information regeneration.First, second, and third wavelength X
1, λ
2And λ
3(λ satisfies condition
1＜λ
2＜λ
3).Object lens include and help the 3rd light beam is converged to first area on the recording surface of the 3rd CD.This first area comprises the phase-shift structure that has around a plurality of coaxial plane of refraction zone that default axle forms.Phase-shift structure comprises first step group and second step group.
In this configuration, it is different with the path length difference that intersection between the adjacent plane of refraction zone of second step group in the second step group is imparted into irradiating light beam that the intersection between the adjacent plane of refraction zone of first step group in the first step group is imparted into the path length difference of irradiating light beam.The first and second optical path difference functions define the position of the step that forms respectively in the first and second step groups.I level optical path difference function phi i (h) is expressed as:
φ
i(h)＝(P
i2h
2+P
i4h
4+P
i6h
6+P
i8h
8+P
i10h
10+P
i12h
12)m
iλ
P wherein
I2, P
I4, P
I6(i: natural number) second rank, quadravalence, the 6th rank of expression i level optical path difference function ... coefficient, h are represented the height apart from optical axis, m
iThe order of diffraction of expression diffraction efficiency maximum, λ represents the design wavelength of incident beam.The first optical path difference function phi
1(h) the second rank FACTOR P
12For on the occasion of.The second optical path difference function phi
2(h) the second rank FACTOR P
22Be negative value.The first step group is configured such that each step of first step group gives the path length difference Δ OPD of first light beam
1(nm) satisfy condition:
2N
1+1.10＜|ΔOPD
1/λ1|＜2N
1+1.40…(1)
N wherein
1Be natural number or zero.
The second step group is configured such that each step of second step group gives the path length difference Δ OPD of first light beam
2(nm) satisfy condition:
2N
2-0.10＜|ΔOPD
2/λ1|＜2N
2+0.10…(2)
N wherein
2Be natural number.
By this configuration, each the light utilization efficiency in first, second, and third CD can be remained on high level.By the second rank coefficient of the first and second optical path difference functions is set according to mode above, can when using first CD, suitably suppress the appearance of longitudinal chromatic aberration.In addition, can reduce the amount of unexpected order of diffraction light, thereby prevent the waveform deterioration of focus error signal.
According to a further aspect in the invention, provide a kind of optical information recorder/transcriber, it is used for comprising having first wavelength X by optionally using
1(nm) first light beam, has second wavelength X
2(nm) second light beam and have a wavelength lambda
3(nm) one of three types of light beams of the 3rd light beam, recorded information and/or information reproduction from it on three types the CD.At least three types CD comprises that use first light beam carries out second CD of information record or information regeneration and uses the 3rd light beam that it is carried out the 3rd CD of information record or information regeneration it first CD, use second light beam that it carries out information record or information regeneration.First, second, and third wavelength X
1, λ
2And λ
3(λ satisfies condition
1＜λ
2＜λ
3).When the numerical aperture with the information regeneration on first, second, and third CD or information record needs is defined as NA1, NA2 and NA3 respectively, and the satisfied relation of numerical aperture (NA1＞NA3); And (NA2＞NA3).When representing the protective layer thickness of first, second, and third CD respectively with t1 (mm), t2 (mm) and t3 (mm), protective layer thickness is t1 ≈ 0.6mm, t2 ≈ 0.6mm and t3 ≈ 1.2mm.The optical disc information data recording/reproducing device comprises the light source that sends first, second, and third light beam respectively; And object lens mentioned above.In this configuration, with, the second and the 3rd light beam each incide on the object lens as collimated light beam.
By this configuration, each the light utilization efficiency in first, second, and third CD can be remained on high level.By the second rank coefficient of the first and second optical path difference functions is set in the manner described above, can when using first CD, suitably suppress the appearance of longitudinal chromatic aberration.In addition, can reduce the amount of unexpected order of diffraction light, thereby prevent the waveform deterioration of focus error signal.
In aspect at least one, the first step group is configured to satisfy condition:
0.0＜f1×P
12＜23.0…(3)
Wherein f1 (mm) expression object lens are about the focal length of first light beam.
In aspect at least one, the second step group is configured to satisfy condition:
-35.0≤f1×P
22＜0.0…(4)。
In aspect at least one, object lens satisfy condition:
-15.0＜f1×(m
1×P
12+m
2×P
22)＜30.0.....(5)。
In aspect at least one, object lens satisfy condition:
-10.0＜f1×(m
1×P
12+m
2×P
22)＜20.0.....(6)。
In aspect at least one, satisfy N1=1 and N2=1.
In aspect at least one, object lens comprise the second area that is positioned at outside the first area.Second area helps first and second light beams are converged to respectively on the recording surface of first and second CDs, and is helpless to the 3rd light beam is converged on the recording surface of the 3rd CD.
Description of drawings
Fig. 1 is the optics block diagram according to optical information recorder/transcriber of embodiment.
Fig. 2 A illustrates the example that the optical texture at aperture diaphragm place is set in object lens the place ahead.
Fig. 2 B is the front view from the aperture diaphragm of first surface side observation.
The curve map of Fig. 3 spherical aberration that to be graphic extension cause when using the CD D1 with tidemark density in according to the optical information recorder/transcriber of first example.
The curve map of Fig. 4 spherical aberration that to be graphic extension cause when using CD D1 in according to the optical information recorder/transcriber of second example.
The curve map of Fig. 5 spherical aberration that to be graphic extension cause when using CD D1 in according to the optical information recorder/transcriber 100 of the 3rd example.
Fig. 6 is focal position and the FACTOR P of the veiling glare in the use of graphic extension CD D1
12Between the curve map of relation.
Fig. 7 A shows the focus error signal in the use of the CD D1 in first example, and Fig. 7 B shows the focus error signal in the use of the CD D3 with all time low density in first example.
Fig. 8 A shows the focus error signal in the use of the CD D1 in second example, and Fig. 8 B shows the focus error signal in the use of the CD D3 in second example.
Fig. 9 A shows the focus error signal in the use of the CD D1 in the 3rd example, and Fig. 9 B shows the focus error signal in the use of the CD D3 in the 3rd example.
Figure 10 is the cross-sectional view of object lens, and it is illustrated in the phase-shift structure that forms on these object lens.
Embodiment
Hereinafter, describe with reference to the accompanying drawings according to embodiments of the invention.
Next, describe according to the object lens 10 of this embodiment and optical information recorder/transcriber 100 (see figure 1)s that object lens 10 have been installed.
In ensuing explanation, for ease of explanation, (for example will have tidemark density, new standard CD such as HD DVD or BD) the CD of a class one of (three types) be called " CD D1 ", to be called " CD D2 " compared to the class CD (DVD, DVD-R etc.) that CD D1 has a low relatively recording density, a class CD (CD, CD-R etc.) that will have all time low density is called " CD D3 ".
If the protective layer thickness of CD D1-D3 is defined as t1, t2, t3 respectively, then protective layer thickness is defined as follows.
t1＝0.6mm
t2＝0.6mm
t3＝1.2mm
Carry out information regeneration/record in CD D1-D3 each, the required NA (numerical aperture) of information regeneration/record must suitably change, thereby can form the bundle spot of the specific recording density that is fit to each CD.When the optimal design numerical aperture that three types CD D1, D2 and the information regeneration on the D3/record are needed was defined as NA1, NA2 and NA3 respectively, numerical aperture (NA1, NA2, NA3) satisfied relation of plane down:
(NA1＞NA3) reach (NA2＞NA3)
Particularly, in order to carry out information recording/regenerating at CD D1 and D2 with high record density, must form less relatively hot spot, therefore need relatively large NA.On the other hand, in order to carry out information recording/regenerating at the CD D3 with all time low density, required relatively little NA.Additional disclosure, when carrying out information recording/regenerating, each CD is placed on the rotating disk (not shown) and rotation at a high speed.
When the CD D1-D3 (having different recording densitys) that uses three types as mentioned above, optical information recorder/transcriber optionally uses the multiple laser bundle with different wave length, thereby can form the bundle spot that is fit to every kind of recording density at the recording surface of the CD that is using.
Particularly, for carrying out information recording/regenerating at CD D1, send " first laser beam " with minimal wave length from light source, in order to form tuftlet spot at the recording surface of CD D1.On the other hand, for carrying out information recording/regenerating at CD D3, send " the 3rd laser beam " with long wavelength from light source, in order to form large beam spot at the recording surface of CD D3.For carrying out information recording/regenerating at CD D2, send " second laser beam " with wavelength long and shorter than the wavelength of the 3rd laser beam than the wavelength of first laser beam from light source, in order to form less relatively bundle spot at the recording surface of CD D2.
Fig. 1 is the optics block diagram of optical information recorder/transcriber 100.Optic recording/reproducing device 100 comprises the light source 1A that sends first laser beam, the light source 2A that sends second laser beam, the light source 3A that sends the 3rd laser beam, collimation lens 20, constitutes object lens 10, beam splitter 41 and 42, half-reflecting mirror 43 and the photoreceptor 44 of objective lens optical system.
As mentioned above, required NA changes according to the type of the CD that is using.Therefore, shown in Fig. 2 A, optical information recorder/transcriber 100 can have the aperture diaphragm of adjusting along the beam diameter of the 3rd laser beam of 10 the light path from light source 3A to object lens 60.
Fig. 2 A illustrates the example that the optical texture at aperture diaphragm 60 places is set in object lens 10 the place aheads.Shown in Fig. 2 A, aperture diaphragm 60 has first surface 61 and the second surface 62 that arranges according to the order from light source side.Fig. 2 B is the front view from the aperture diaphragm 60 of first surface 61 these sides observations.Shown in Fig. 2 B, first surface 61 is included in first and second transparent region 63a and the 63b that coaxial boundary is separated from each other.The first transparent region 63a has the characteristic of each bundle from wherein passing through that allows in first to the 3rd laser beam.The second transparent region 63b has and only allows first and second laser beam from wherein by stopping the characteristic of the 3rd laser beam.
When from this side observation aperture of second surface 62 diaphragm 60, can observe and situation identical shown in Fig. 2 B.
By using aperture diaphragm 60, the diameter of the 3rd laser beam can be decreased to preset diameters.That is to say, can form the bundle spot with required diameter at CD D3.
For CD D1-D3 being carried out information record or information regeneration, the common light path of each bundle guiding in first or second laser beam of light source 1A and 2A being sent by beam splitter 42 and 41, this common light path of the 3rd laser beam direction of light source 3A being sent by beam splitter 41.Then, collimation lens 20 is with each the bundle collimation in first to the 3rd laser beam.Every bundle laser beam by collimation lens 20 enters object lens 10.
The reference axis AX that in Fig. 1, represents optical information recorder/transcriber 100 with dot-and-dash line.Although the optical axis of object lens 10 overlaps with reference axis AX in Fig. 1, also there is the situation of the optical axis deviation reference axis AX of object lens 10, for example by this situation of tracking (tracking) caused by operations in the implementation of information record or information regeneration.
Be converged to collimated light beam like this by each bundle in first to the 3rd laser beam that will enter object lens 10, can prevent from occurring off-axis aberration at object lens 10 owing to following the tracks of to operate under the state that departs from reference axis AX, for example coma.
Laser beam by object lens 10 converges near the point the recording surface of the CD that is using.The recording surface of each among the CD D1-D3 is clipped between protective seam and the label layer.
Move on along same common light path from the laser beam of the CD reflection used, and by beam splitter 41 and 42 and half-reflecting mirror 43 after by photoreceptor 44 detections.
As mentioned above, when CD D1-D3 optionally being used when having the different wavelength of laser bundle, spherical aberration changes according to the difference of the protective layer thickness between the CD D1-D3 or the change of refractive of object lens 10.
Therefore, object lens 10 are configured to by being each correcting spherical aberration among the CD D1-D3, and the compatibility to three types CD D1-D3 is provided.In order to obtain this optical property, object lens 10 possess following feature.
As shown in Figure 1, object lens 10 have surface 11 and the surface 12 that arranges according to the order from light source side.Object lens 10 are the biconvex single element lens that are made of plastics.The surface 11 and 12 of object lens 10 is aspheric surface.
Aspheric shape is represented with following formula:
Wherein, X (h) expression SAG amount is selecting of h and the distance of aspheric surface between the tangent plane at optical axis place apart from the optical axis height on the aspheric surface namely, and symbol c represents the curvature (1/r) on the optical axis, and K is the circular cone coefficient, A
2j(j; Integer more than or equal to 2) expression the 4th rank, the 6th rank, the 8th rank, the 10th rank, the 12nd rank ... asphericity coefficient.
One of at least be provided with the phase-shift structure that has around a plurality of coaxial plane of refraction zone (annulus) that optical axis forms in the surface 11 and 12 of object lens 10.Mark off a plurality of annuluses by small step, described small step is formed between the adjacent annular district of a plurality of annuluses.In the present embodiment, the annulus structure is formed on the surface 11.
Step in the phase-shift structure minute is claimed a plurality of step groups, and these step groups are imparted into the mutually different path length difference of irradiating light beam.In the present embodiment, the phase-shift structure of object lens 10 comprises two types step group (the first and second step groups).
More specifically, the first step group is configured such that each step of first step group gives the path length difference Δ OPD of first laser beam
1Satisfy condition:
2N
1+1.10＜|ΔOPD
1/λ1|＜2N
1+1.40…(1)
N wherein
1Be natural number or zero.
Condition (1) is the condition for the light utilization efficiency that improves CD D3.If the middle entry of the condition (1) that the first step group is limited (| Δ OPD
1/ λ 1|) be less than or equal to the lower limit of condition (1), then the light utilization efficiency of CD D3 can be lower than about 50%.If the middle entry of the condition (1) that the first step group is limited is more than or equal to the upper limit of condition (1), then the light utilization efficiency of CD D1 can be lower than about 70%.Path length difference (Δ OPD for example
1) refer in the defined distance of the optical axis direction of object lens 10.When phase-shift structure (being annulus) forms at curved surface, the height of step is not the value (height that is each stage rank is not constant) with constant and provide the optical path difference of constant.
As mentioned above, if do not satisfy condition (1), then can not guarantee in CD D1 and D3 each the information record and information regeneration enough light quantities.In this case, can't obtain stable information recording/regenerating.
The second step group is configured such that each step of second step group gives the path length difference Δ OPD of first laser beam
2Satisfy condition:
2N
2-0.10＜|ΔOPD
2/λ1|＜2N
2+0.10…(2)
N wherein
2It is natural number.
Condition (2) is the condition for the light utilization efficiency of each of raising CD D1 and D2.If the middle entry of the condition (2) that the second step group is limited (| Δ OPD
2/ λ 1|) be less than or equal to the lower limit of condition (2), then the light utilization efficiency of CD D1 can be lower than about 95%.If the middle entry of the condition (2) that the second step group is limited is more than or equal to the upper limit of condition (2), then the light utilization efficiency of CD D2 can be lower than about 85%.
As mentioned above, if do not satisfy condition (2), then can not guarantee in CD D1 and D2 each the information record and the enough light quantities the information regeneration.In this case, can't obtain stable information recording/regenerating.
Next explain the design of the phase-shift structure with polytype step group.
At first, calculate polytype optical path difference function, make and to get ratio between the order of diffraction at maximal value place separately (hereafter is " order of diffraction than ") about the diffraction efficiency of first to the 3rd laser beam, polytype optical path difference function has mutually different order of diffraction ratio.In the present embodiment, calculate two types optical path difference function (the first and second optical path difference functions) according to following mode.
The optical path difference function with the form of the additional optical distance at distance optical axis height h place as the diffraction lens representative function.More specifically, i level optical path difference function phi i (h) can represent with following formula:
φ
i(h)＝(P
i2h
2+P
i4h
4+P
i6h
6+P
i8h
8+P
i10h
10+P
i12h
12)m
iλ
P wherein
I2, P
I4, P
I6(i: natural number) the 2nd rank, the 4th rank, the 6th rank of expression i level optical path difference function ... coefficient, h are represented the height apart from optical axis, m
iThe order of diffraction of expression diffraction efficiency maximum, λ represents the design wavelength of the laser beam used.
Calculated after two types the optical path difference function, the optical path difference function has been joined together to determine the shape of phase-shift structure.By the optical path difference function design phase-shift structure of two types of such usefulness, two types the step group that can obtain giving the mutually different path length difference of first laser beam.
As mentioned above, provide the light utilization efficiency of condition (1) with main raising CD D3.Therefore, the first step group of (1) of satisfying condition is configured to have relatively large step dimension.For this reason, the first step group can not be given security light utilization efficiency to the information of CD D1 record and information regeneration in enough effects of level.That is to say that the first step group may cause veiling glare to a certain degree.
This veiling glare may reduce the signal to noise ratio (S/N ratio) of the focus error signal that relies on convergent point.Therefore, need the convergent point of control veiling glare, make veiling glare can not have a strong impact on the signal to noise ratio (S/N ratio) of focus error signal.It is to use the CD D1 with the sandwich construction that is commonly used to increase memory capacity in optical information recorder/transcriber 100 that kind of possibility is arranged.Therefore, even when use has the CD D1 of sandwich construction, also need to control the convergent point of veiling glare, remain on high level with the signal to noise ratio (S/N ratio) with focus error signal.
For the CD D1 that will have single layer structure and the two veiling glare of CD D1 with sandwich construction all converge to the position that can not reduce the signal to noise ratio (S/N ratio) of focus error signal, will limit the FACTOR P of the first optical path difference function of first step group
12Be made as have on the occasion of.In this case, paraxial diffraction multiplying power is got negative value.By this configuration, the veiling glare that produces in the use of CD D1 is converged onto the convergent point position overlapped with normal order of diffraction light.
More specifically, the first step group is configured to satisfy following conditions (3):
0.0＜f1×P
12＜23.0…(3)
Wherein f1 represents that object lens 10 are about the focal length of first laser beam.
By limiting FACTOR P
12Satisfy condition (3), even when use has the CD D1 of sandwich construction, also veiling glare can be converged to the position that can not have a strong impact on the signal to noise ratio (S/N ratio) of focus error signal.Ensuing explanation is further concentrated and is discussed this viewpoint.
Next, the sandwich construction of supposing CD D1 comprises according to tactic first recording layer and second recording layer from light source side.Work as FACTOR P
12When satisfying condition (3), the veiling glare that one of first and second recording layers are assembled does not converge on the position of another recording layer among first and second recording layers.Therefore, when satisfying condition (3), can prevent effectively that veiling glare that one of first and second recording layers are assembled from occurring as the noise of focus error signal.
But, if the FACTOR P of the first optical path difference function
12Get on the occasion of, then the longitudinal chromatic aberration that produces when using CD D1 is in the state of undercorrection.For this reason, the FACTOR P of the second optical path difference function of second step group will be limited
22Be made as and have negative value, in order to suitably proofread and correct the longitudinal spherical aberration that the control by the veiling glare focal position causes.
More specifically, the second step group is configured such that FACTOR P
22Satisfy following conditions (4).
-35.0≤f1×P
22＜0.0…(4)
If the intermediate value (f1 * P of condition (4)
22) be lower than the lower limit of condition (4), then the multiplying power of the phase-shift structure of first laser beam can be too strong, thus longitudinal spherical aberration is in the state of excessive correction.If the intermediate value of condition (4) more than or equal to the upper limit of condition (4) (that is, if FACTOR P
22Get on the occasion of), the function of then proofreading and correct longitudinal chromatic aberration can not work effectively.
In order in the focal position of control veiling glare, suitably to proofread and correct longitudinal chromatic aberration, can be with FACTOR P
12And P
22Be made as and satisfy following conditions (5) and (6).
-15.0＜f1×(m
1×P
12+m
2×P
22)＜30.0…(5)
-10.0＜f1×(m
1×P
12+m
2×P
22)＜20.0…(6)
By phase-shift structure being configured to satisfy above-mentioned condition, be used as collimated light beam even will enter first to the 3rd laser beam of object lens 10, also can be suitably to each the inhibition spherical aberration among the CD D1-D3.In addition, also can suitably suppress to follow the tracks of coma or the astigmatism that causes in the operating process.In addition, when using CD D1, can in the veiling glare that prevents unexpected order of diffraction light, keep suitable focusing function.
Needn't form above-mentioned phase-shift structure at whole surperficial 11 of object lens 10.Can in the inside that is limited at the surface 11 that comprises optical axis and the zone (hereinafter being called the first area) that helps the 3rd laser beam to assemble, form phase-shift structure.In other words, the first area is restricted to the innermost zone of each beam convergence that helps first, second, and third laser beam.
As described in detail below, in order to guarantee that object lens 10 are configured to have different structure according to the position of beam effective diameter restriction to each information record and the required NA of information regeneration among the CD D1-D3.For example, object lens 10 can be configured to have second area, and this second area is arranged in outside the first area and has the phase-shift structure different with the phase-shift structure of first area.
Phase-shift structure in the second area is configured to respectively first and second laser beam suitably be converged on the recording surface 22 of CD D1 and D2.It should be noted that each bundle in first and second laser beam be respectively applied to need be than the numerical aperture of CD D3 CD D1 and the D2 of higher numerical aperture.
Phase-shift structure in the second area has the step that is helpless to the convergence of the 3rd laser beam.That is to say that about first laser beam, the absolute value one of at least in polytype path length difference that second area is given is different with the absolute value of the path length difference that the specific step group in the first area is given.About first laser beam, if polytype step group is limited in the first area, then the specific step group in the first area is equivalent to give the step group near the path length difference of the even-multiple of the wavelength of first laser beam.For example, if there are two kinds of step groups in the first area, the step group of then satisfy condition (2) (being the second step group) is equivalent to specific step group.
Figure 10 is the conceptual illustration at the phase-shift structure of the surface of object lens 10 11 formation.That is to say that Figure 10 is the cross-sectional view of object lens 10, it is illustrated in the phase-shift structure that forms on the surface 11 of object lens 10.In Figure 10, illustrate first and second zones.Because the purpose of Figure 10 is to provide conceptual phase-shift structure figure, phase-shift structure is depicted as the step formation first area of single type in Figure 10.Yet as indicated above, the first area can comprise polytype step.
Next, three concrete examples of the optical information recorder/transcriber 100 that uses object lens 10 are described.Each optics block diagram in ensuing three examples has been shown among Fig. 1.
In ensuing three examples, use aperture diaphragm shown in Figure 2 60 confine optical beam diameters, thereby obtain to be suitable for the information record of CD D3 and the numerical aperture of information regeneration.In ensuing three examples, the protective layer thickness of CD D1, D2 and D3 limits as follows.
D1＝0.6mm，D2＝0.6mm，D3＝1.2mm
First example
Following table 1 has shown the concrete specification according to the object lens 10 of first example.
Table 1
| First laser beam | Second laser beam | The 3rd laser beam | |
| Wavelength (nm) | 406 | 660 | 788 |
| Focal length (mm) | 2.0 | 2.08 | 2.09 |
| NA | 0.65 | 0.63 | 0.50 |
| Enlargement ratio M | 0.000 | 0.000 | 0.000 |
Shown in " enlargement ratio M " in the table 1, during in using CD D1-D3 each, laser beam incides on the object lens 10 as collimated light beam.
Table 2 has shown the concrete numerical value configuration that limits when using CD D1 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 1.Below table 3 shown the concrete numerical value configuration that when using CD D2 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 1, limits.Following table 4 has shown the concrete numerical value configuration that limits when using CD D3 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 1.
Table 2
Table 3
Table 4
In table 2-4 (and in following similar table), " r " represents the radius-of-curvature (mm) of each optical surface, " d " is illustrated in thickness or the distance from each optical surface to next optical surface (mm) of the optical module in information regeneration/recording process, and " n (Xnm) " is illustrated in the refractive index of wavelength Xnm.
In table 2-4, surperficial # 1 and #2 represent the surface 11 and 12 of object lens 10 respectively, and surperficial #3 and #4 represent protective seam and the recording surface of corresponding CD.
In the surface 11 and 12 of object lens 10 (surperficial # 1 and #2) each all is aspheric surface.Following table 5 has shown each constant of the cone K and the asphericity coefficient A of shape in the surface 11 and 12 (surperficial # 1 and #2) of definite object lens 10
2iIn table 5 (and in following similar table), it be the truth of a matter with the numeral on E right side is that (for example " E-04 " means " * 10 for the power of index that symbol " E " means with 10
-4").
Table 5
The surface 11 of object lens 10 has the first area that comprises optical axis and the second area that is positioned at outside the first area.As followsly limit first and second zones by the height apart from optical axis.
First area: 0.000≤h≤1.050
Second area: 1.050＜h≤1.300
The first area is the common region that helps each beam convergence of first to the 3rd laser beam.Second area help first and second laser beam each bundle convergence and be helpless to the convergence of the 3rd laser beam.In other words, second area has served as the aperture diaphragm of the 3rd laser beam.
First and second zones have the function that differs from one another.That is to say that each of first and second zones has unique phase-shift structure.More specifically, each of first and second zones has the phase-shift structure that is limited by mutually different two types optical path difference function as follows.Shown each the coefficient (Pi2 of two types optical path difference function phi i (h) that limits first and second zones in following table 6 and the table 7 ...) and order of diffraction m.
Table 6
Table 7
| Surface number | First laser beam | Second laser beam | The 3rd laser beam |
| First area (i=1) | 3 | 2 | 2 |
| First area (i=2) | 2 | 1 | 1 |
| Second area (i=1) | 3 | 2 | 2 |
| Second area (i=2) | 5 | 3 | 3 |
Second example
Following table 8 has shown the concrete specification according to the object lens 10 of second example.
Table 8
| First laser beam | Second laser beam | The 3rd laser beam | |
| Wavelength (nm) | 406 | 660 | 788 |
| Focal length (mm) | 2.00 | 2.07 | 2.08 |
| NA | 0.65 | 0.63 | 0.50 |
| Enlargement ratio M | 0.000 | 0.000 | 0.000 |
Shown in " enlargement ratio M " in the table 1, during in using CD D1-D3 each, laser beam incides on the object lens 10 as collimated light beam.
Table 9 has shown the concrete numerical value configuration that limits when using CD D1 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 8.Below table 10 shown the concrete numerical value configuration that when using CD D2 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 8, limits.Below table 11 shown the concrete numerical value configuration that when using CD D3 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 8, limits.
Table 9
Table 10
Table 11
In table 9-11, surperficial # 1 and #2 represent the surface 11 and 12 of object lens 10 respectively, and surperficial #3 and #4 represent protective seam and the recording surface of corresponding CD.
In the surface 11 and 12 of object lens 10 (surperficial # 1 and #2) each all is aspheric surface.Following table 12 has shown each constant of the cone K and the asphericity coefficient A of shape in the surface 11 and 12 (surperficial # 1 and #2) of definite object lens 10
2i
Table 12
The surface 11 of object lens 10 has the first area that comprises optical axis and the second area that is positioned at outside the first area.As followsly limit first and second zones by the height apart from optical axis.
First area: 0.000≤h≤1.050
Second area: 1.050＜h≤1.300
The first area is the common region that helps each beam convergence of first to the 3rd laser beam.Second area help first and second laser beam each bundle convergence and be helpless to the convergence of the 3rd laser beam.In other words, second area has served as the aperture diaphragm of the 3rd laser beam.
First and second zones have the function that differs from one another.That is to say that each of first and second zones has unique phase-shift structure.More specifically, each of first and second zones has the phase-shift structure that is limited by mutually different two types optical path difference function as follows.Shown each the coefficient (Pi2 of two types optical path difference function phi i (h) that limits first and second zones in following table 13 and the table 14 ...) and order of diffraction m.
Table 13
Table 14
| Surface number | First laser beam | Second laser beam | The 3rd laser beam |
| First area (i=1) | 3 | 2 | 2 |
| First area (i=2) | 2 | 1 | 1 |
| Second area (i=1) | 3 | 2 | 2 |
| Second area (i=2) | 5 | 3 | 3 |
The 3rd example
Following table 15 has shown the concrete specification according to the object lens 10 of the 3rd example.
Table 15
| First laser beam | Second laser beam | The 3rd laser beam | |
| Wavelength (nm) | 406 | 660 | 788 |
| Focal length (mm) | 2.00 | 2.10 | 2.11 |
| NA | 0.65 | 0.62 | 0.50 |
| Enlargement ratio M | 0.000 | 0.000 | 0.000 |
Shown in " enlargement ratio M " in the table 1, during in using CD D1-D3 each, laser beam incides on the object lens 10 as collimated light beam.
Table 16 has shown the concrete numerical value configuration that limits when using CD D1 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 15.Below table 17 shown the concrete numerical value configuration that when using CD D2 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 15, limits.Below table 18 shown the concrete numerical value configuration that when using CD D3 in the optical information recorder/transcriber 100 with the object lens 10 shown in the table 15, limits.
Table 16
Table 17
Table 18
In table 16-18, surperficial # 1 and #2 represent the surface 11 and 12 of object lens 10 respectively, and surperficial #3 and #4 represent protective seam and the recording surface of corresponding CD.
In the surface 11 and 12 of object lens 10 (surperficial # 1 and #2) each all is aspheric surface.Following table 19 has shown each constant of the cone K and the asphericity coefficient A of shape in the surface 11 and 12 (surperficial # 1 and #2) of definite object lens 10
2i
Table 19
The surface 11 of object lens 10 has the first area that comprises optical axis and the second area that is positioned at outside the first area.As followsly limit first and second zones by the height apart from optical axis.
First area: 0.000≤h≤1.050
Second area: 1.050＜h≤1.300
The first area is the common region that helps each beam convergence of first to the 3rd laser beam.Second area help first and second laser beam each bundle convergence and be helpless to the convergence of the 3rd laser beam.In other words, second area has served as the aperture diaphragm of the 3rd laser beam.
First and second zones have the function that differs from one another.That is to say that each of first and second zones has unique phase-shift structure.More specifically, each of first and second zones has the phase-shift structure that is limited by mutually different two types optical path difference function as follows.Shown each the coefficient (Pi2 of two types optical path difference function phi i (h) that limits first and second zones in following table 20 and the table 21 ...) and order of diffraction m.
Table 20
Table 21
| Surface number | First laser beam | Second laser beam | The 3rd laser beam |
| First area (i=1) | 3 | 2 | 2 |
| First area (i=2) | 2 | 1 | 1 |
| Second area (i=1) | 3 | 2 | 2 |
| Second area (i=2) | 5 | 3 | 3 |
The optical property of first to the 3rd example is described hereinafter.To in first to the 3rd example each, following table 22 shows condition (1) to the value of the middle entry of (6).The curve map of Fig. 3 spherical aberration that to be graphic extension cause when using CD D1 in according to the optical information recorder/transcriber 100 of first example.The curve map of Fig. 4 spherical aberration that to be graphic extension cause when using CD D1 in according to the optical information recorder/transcriber 100 of second example.The curve map of Fig. 5 spherical aberration that to be graphic extension cause when using CD D1 in according to the optical information recorder/transcriber 100 of the 3rd example.In in Fig. 3-5 each, curve table shown in the solid line is shown in the sphere that design wavelength 407nm place causes and differs, curve table shown in the dotted line is shown in the sphere that wavelength 412nm place causes and differs, and the curve table shown in the dot-and-dash line is shown in the sphere that wavelength 402nm place causes and differs.
Table 22
| First example | Second example | The 3rd example | |
| Condition (1) | 3.25 | 3.36 | 3.15 |
| Condition (2) | 1.97 | 1.93 | 2.07 |
| Condition (3) | 8.6 | 1.0 | 22.2 |
| Condition (4) | -12.0 | -1.0 | -33.0 |
| Condition (5) | 1.8 | 1.0 | 0.6 |
| Condition (6) | 1.8 | 1.0 | 0.6 |
Shown in table 22, (1)-(6) that all satisfy condition of each in first to the 3rd example.Therefore, shown in Fig. 3-5, the sphere difference correction is extremely suitable design wavelength.In addition, even when the wavelength of laser beam a little during the off-design wavelength, sphere differs with longitudinal chromatic aberration and is also all suitably suppressed.
Fig. 6 is convergent point and the FACTOR P of the veiling glare in the use of graphic extension CD D1
12Between the curve map of relation.Limit the convergent point of veiling glare shown in Figure 6 with respect to the convergent point (being the position of the recording surface of CD D1) of normal order of diffraction light.About first example, the some FP1 be illustrated in the above-mentioned relation that limits in first example, the convergent point of veiling glare be as shown in Figure 6-0.004mm.About second example, the some FP2 be illustrated in the above-mentioned relation that limits in second example, the convergent point of veiling glare be as shown in Figure 6-0.017mm.About the 3rd example, some FP3 is illustrated in the above-mentioned relation that limits in the 3rd example, and the convergent point of veiling glare is 0.018mm as shown in Figure 6.
Usually, the CD (the CD D3 that namely has sandwich construction) that has for increasing the type of the sandwich construction of recording density is configured to have the spacing of 20 μ m to 40 μ m between adjacent recording layer.In this, certainly, the convergent point of the veiling glare that produces when using CD D1 is located between the adjacent recording layer.That is to say, veiling glare is converged to the position that does not cause the noise on the focus error signal.
Fig. 7 A and Fig. 7 B show the focus error signal of first example, and Fig. 8 A and Fig. 8 B show the focus error signal of second example, and Fig. 9 A and Fig. 9 B show the focus error signal of the 3rd example.More specifically, Fig. 7 A shows the focus error signal in the use of the CD D1 in first example, and Fig. 7 B shows the focus error signal in the use of the CD D3 in first example.Fig. 8 A shows the focus error signal in the use of the CD D1 in second example, and Fig. 8 B shows the focus error signal in the use of the CD D3 in second example.Fig. 9 A shows the focus error signal in the use of the CD D1 in the 3rd example, and Fig. 9 B shows the focus error signal in the use of the CD D3 in the 3rd example.
Owing to the position that veiling glare is converged between the adjacent recording layer, so Fig. 7 A, 7B, 8A, 8B, 9A and 9B have shown the suitable serpentine curve that normal order of diffraction light forms.That is to say that each in the focus error signal of first to the 3rd example all has high s/n ratio.
Though quite describe the present invention in detail with reference to specific preferred embodiment, other embodiment also are possible.
Configuration according to the object lens 10 of present embodiment is not limited to the configuration shown in first to the 3rd example.The optical module that has in optical information recorder/transcriber 100 (for example objective lens optical system) can be made of a plurality of optical elements.If objective lens optical system is made of a plurality of optical elements, then the optical element according to above-described embodiment design can have phase-shift structure in front and rear surfaces respectively.That is to say that object lens 10 can all have phase-shift structure on surface 11 and 12.
According to the type of employed standard, be used for the NA of CD D1 and the difference that is used between the NA of CD D2 can be very big.In other words, the different situation of effective diameter of second laser beam on the surface 11 of the effective diameter that has first laser beam on the surface 11 of object lens 10 and object lens 10.In this case, can outside second area, be provided for guaranteeing the 3rd zone of higher NA (namely bigger effective diameter).
For example, if the required NA of CD D1 then disposes the 3rd zone and assembles the convergence that first laser beam is helpless to the laser beam of other types effectively for only helping greater than the required NA of CD D2.
Claims (13)
1. object lens that are used for optical information recorder/transcriber, this optical information recorder/transcriber is used for comprising having first wavelength X by optionally using
1First light beam, have second wavelength X
2Second light beam and have a wavelength lambda
3One of three types the light beam of the 3rd light beam, recorded information and/or information reproduction from it on three types the CD,
Three types CD comprises that use first light beam carries out second CD of information record or information regeneration and uses the 3rd light beam that it is carried out the 3rd CD of information record or information regeneration it first CD, use second light beam that it carries out information record or information regeneration
First, second, and third wavelength X
1, λ
2And λ
3Satisfy condition:
λ
1＜λ
2＜λ
3，
Object lens include and help the 3rd light beam is converged to first area on the recording surface of the 3rd CD,
The first area comprises the phase-shift structure that has around a plurality of coaxial plane of refraction zone that default axle forms,
Phase-shift structure comprises first step group and second step group,
Wherein:
The path length difference that is imparted into irradiating light beam between the path length difference that is imparted into irradiating light beam between the adjacent plane of refraction zone of first step group in the first step group and the adjacent plane of refraction zone of second step group in the second step group is different;
The first and second optical path difference functions define the position of the step that forms respectively in the first and second step groups;
I optical path difference function phi i (h) is expressed as:
φ
i(h)＝(P
i2h
2+P
i4h
4+P
i6h
6+P
i8h
8+P
i10h
10+P
i12h
12)m
iλ
I wherein: natural number, P
I2, P
I4, P
I6, represent second rank, quadravalence, the 6th rank of i optical path difference function respectively ... coefficient, h are represented the height apart from optical axis, m
iThe order of diffraction of expression diffraction efficiency maximum, λ represents the design wavelength of incident beam;
The first optical path difference function phi
1(h) the second rank FACTOR P
12For on the occasion of;
The second optical path difference function phi
2(h) the second rank FACTOR P
22Be negative value;
The first step group is configured such that each step of first step group gives the path length difference Δ OPD of first light beam
1Satisfy condition:
2N
1+1.10＜|ΔOPD
1/λ1|＜2N
1+1.40 (1)
N wherein
1Be natural number or zero; And
The second step group is configured such that each step of second step group gives the path length difference Δ OPD of first light beam
2Satisfy condition:
2N
2-0.10＜|ΔOPD
2/λ1|＜2N
2+0.10 (2)
N wherein
2Be natural number.
2. object lens according to claim 1,
Wherein the first step group is configured to satisfy condition:
0.0＜f1×P
12＜23.0 (3)
Wherein f1 represents that object lens are about the focal length of first light beam.
3. object lens according to claim 1,
Wherein the second step group is configured to satisfy condition:
-35.0≤f1×P
22＜0.0 (4)
Wherein f1 represents that object lens are about the focal length of first light beam.
4. object lens according to claim 1,
Wherein object lens satisfy condition:
-15.0＜f1×(m
1×P
12+m
2×P
22)＜30.0 (5)
Wherein f1 represents that object lens are about the focal length of first light beam, m
1The order of diffraction of expression diffraction efficiency maximum for the first optical path difference function, m
2The order of diffraction of expression diffraction efficiency maximum for the second optical path difference function.
5. object lens according to claim 4,
Wherein object lens satisfy condition:
-10.0＜f1×(m
1×P
12+m
2×P
22)＜20.0 (6)。
6. object lens according to claim 1 wherein satisfy N1=1 and N2=1.
7. optical information recorder/transcriber, it is used for comprising having first wavelength X by optionally using
1First light beam, have second wavelength X
2Second light beam and have a wavelength lambda
3One of three types the light beam of the 3rd light beam, recorded information and/or information reproduction from it on three types the CD,
Three types CD comprises that use first light beam carries out second CD of information record or information regeneration and uses the 3rd light beam that it is carried out the 3rd CD of information record or information regeneration it first CD, use second light beam that it carries out information record or information regeneration
First, second, and third wavelength X
1, λ
2And λ
3Satisfy condition:
λ
1＜λ
2＜λ
3，
When the numerical aperture with the information regeneration on first, second, and third CD or information record needs was defined as NA1, NA2 and NA3 respectively, numerical aperture satisfied relation of plane down:
NA1＞NA3; And
NA2＞NA3，
When representing the protective layer thickness of first, second, and third CD respectively with t1, t2 and t3, protective layer thickness is t1 ≈ 0.6mm, t2 ≈ 0.6mm and t3 ≈ 1.2mm,
The optical disc information data recording/reproducing device comprises:
Send the light source of first, second, and third light beam respectively; And
Object lens,
Object lens include and help the 3rd light beam is converged to first area on the recording surface of the 3rd CD,
The first area comprises the phase-shift structure that has around a plurality of coaxial plane of refraction zone that default axle forms,
Phase-shift structure comprises first step group and second step group,
Wherein:
The path length difference that is imparted into irradiating light beam between the path length difference that is imparted into irradiating light beam between the adjacent plane of refraction zone of first step group in the first step group and the adjacent plane of refraction zone of second step group in the second step group is different;
The first and second optical path difference functions define the position of the step that forms respectively in the first and second step groups;
I optical path difference function phi i (h) is expressed as:
φ
i(h)＝(P
i2h
2+P
i4h
4+P
i6h
6+P
i8h
8+P
i10h
10+P
i12h
12)m
iλ
I wherein: natural number, P
I2, P
I4, P
I6, represent second rank, quadravalence, the 6th rank of i optical path difference function respectively ... coefficient, h are represented the height apart from optical axis, m
iThe order of diffraction of expression diffraction efficiency maximum, λ represents the design wavelength of incident beam;
The first optical path difference function phi
1(h) the second rank FACTOR P
12For on the occasion of;
The second optical path difference function phi
2(h) the second rank FACTOR P
22Be negative value;
The first step group is configured such that each step of first step group gives the path length difference Δ OPD of first light beam
1Satisfy condition:
2N
1+1.10＜|ΔOPD
1/λ1|＜2N
1+1.40 (1)
N wherein
1Be natural number or zero; And
The second step group is configured such that each step of second step group gives the path length difference Δ OPD of first light beam
2Satisfy condition:
2N
2-0.10＜|ΔOPD
2/λ1|＜2N
2+0.10 (2)
N wherein
2Be natural number, and
Each of first, second, and third light beam is incided on the object lens as collimated light beam.
8. optical information recorder/transcriber according to claim 7,
Wherein the first step group of object lens is configured to satisfy condition:
0.0＜f1×P
12＜23.0 (3)
Wherein f1 represents that object lens are about the focal length of first light beam.
9. optical information recorder/transcriber according to claim 7,
Wherein the second step group of object lens is configured to satisfy condition:
-35.0≤f1×P
22＜0.0 (4)
Wherein f1 represents that object lens are about the focal length of first light beam.
10. optical information recorder/transcriber according to claim 7,
Wherein object lens satisfy condition:
-15.0＜f1×(m
1×P
12+m
2×P
22)＜30.0 (5)
Wherein f1 represents that object lens are about the focal length of first light beam, m
1The order of diffraction of expression diffraction efficiency maximum for the first optical path difference function, m
2The order of diffraction of expression diffraction efficiency maximum for the second optical path difference function.
11. optical information recorder/transcriber according to claim 10,
Wherein object lens satisfy condition:
-10.0＜f1×(m
1×P
12+m
2×P
22)＜20.0 (6)。
12. optical information recorder/transcriber according to claim 7 wherein satisfies N1=1 and N2=1.
13. optical information recorder/transcriber according to claim 7,
Wherein:
Object lens comprise the second area that is positioned at outside the first area; And
Second area helps first and second light beams are converged to respectively on the recording surface of first and second CDs, and is helpless to the 3rd light beam is converged on the recording surface of the 3rd CD.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007-320829 | 2007-12-12 | ||
| JP2007320829 | 2007-12-12 | ||
| JP2007320829A JP5199655B2 (en) | 2007-12-12 | 2007-12-12 | Objective lens for optical information recording / reproducing apparatus and optical information recording / reproducing apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101458940A CN101458940A (en) | 2009-06-17 |
| CN101458940B true CN101458940B (en) | 2013-09-25 |
Family
ID=40753073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200810185762.8A Expired - Fee Related CN101458940B (en) | 2007-12-12 | 2008-12-10 | Objective lens and optical information recording/reproducing device having the same |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US8279738B2 (en) |
| JP (1) | JP5199655B2 (en) |
| CN (1) | CN101458940B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010027183A (en) * | 2008-07-24 | 2010-02-04 | Hoya Corp | Objective lens for optical information recording and reproducing device and optical information recording and reproducing device |
| JP5199835B2 (en) | 2008-11-04 | 2013-05-15 | Ｈｏｙａ株式会社 | Objective lens for optical information recording / reproducing apparatus, and optical information recording / reproducing apparatus |
| US8121012B2 (en) * | 2008-11-19 | 2012-02-21 | Hoya Corporation | Objective lens and optical information recording/reproducing apparatus |
| JP5584552B2 (en) * | 2009-12-21 | 2014-09-03 | Ｈｏｙａ株式会社 | Objective lens for optical information recording / reproducing apparatus, and optical information recording / reproducing apparatus |
| JP5300769B2 (en) * | 2010-03-24 | 2013-09-25 | Ｈｏｙａ株式会社 | Objective lens for optical information recording / reproducing apparatus, and optical information recording / reproducing apparatus |
| JP2013041659A (en) * | 2011-07-15 | 2013-02-28 | Hoya Corp | Objective optical system for optical information recording and reproducing apparatus, and optical information recording and reproducing apparatus |
| CN113206950B (en) * | 2021-04-12 | 2022-05-31 | 中国科学院上海光学精密机械研究所 | High-speed tracking method for micro-nano structure graphic sample |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1571039A (en) * | 2003-04-25 | 2005-01-26 | 宾得株式会社 | Optical system of optical pick-up |
| CN1896773A (en) * | 2005-07-12 | 2007-01-17 | 宾得株式会社 | Optical disc drive and objective lens for the same |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ATE441183T1 (en) | 1999-01-22 | 2009-09-15 | Konica Minolta Opto Inc | OPTICAL SCANNING DEVICE, RECORDING/RECORDING DEVICE EQUIPPED WITH THE OPTICAL SCANNING DEVICE, OPTICAL ELEMENT AND METHOD FOR DATA RECORDING/REPRODUCTION |
| JP3794229B2 (en) * | 1999-01-22 | 2006-07-05 | コニカミノルタホールディングス株式会社 | OPTICAL PICKUP DEVICE, RECORDING / REPRODUCING DEVICE EQUIPPED WITH THE OPTICAL PICKUP DEVICE, INFORMATION RECORDING / REPRODUCING METHOD, AND OBJECTIVE LENS FOR OPTICAL PICKUP DEVICE |
| JP4610118B2 (en) | 2001-03-30 | 2011-01-12 | Ｈｏｙａ株式会社 | Objective lens for optical head |
| US7577077B2 (en) * | 2002-09-05 | 2009-08-18 | Konica Corporation | Optical pickup apparatus and optical element |
| US7414948B2 (en) | 2003-07-29 | 2008-08-19 | Hoya Corporation | Objective lens |
| JP2005174416A (en) | 2003-12-09 | 2005-06-30 | Konica Minolta Opto Inc | Diffraction optical element, objective optical system, optical pickup device and optical information recording reproducing device |
| TWI404060B (en) | 2004-12-01 | 2013-08-01 | Hoya Corp | Optical device for optical disc drive, objective lens, optical disc drive, optical system and design method of optical element. |
| JP4562645B2 (en) * | 2004-12-01 | 2010-10-13 | Ｈｏｙａ株式会社 | Optical element design method and optical information recording / reproducing apparatus |
| JP4992103B2 (en) * | 2004-12-02 | 2012-08-08 | コニカミノルタアドバンストレイヤー株式会社 | Objective optical system, optical pickup device, and optical information recording / reproducing device |
| US7742370B2 (en) | 2005-05-23 | 2010-06-22 | Hoya Corporation | Objective lens and optical information read/write device |
| JP4828303B2 (en) | 2005-05-23 | 2011-11-30 | Ｈｏｙａ株式会社 | Objective lens for optical information recording / reproducing apparatus and optical information recording / reproducing apparatus |
| JP4849979B2 (en) * | 2005-07-12 | 2012-01-11 | Ｈｏｙａ株式会社 | Objective lens for optical information recording / reproducing apparatus and optical information recording / reproducing apparatus |
| CN1941121B (en) | 2005-09-28 | 2010-12-29 | Hoya株式会社 | Optical disc drive and objective lens for the same |
| JP4849939B2 (en) | 2006-04-10 | 2012-01-11 | Ｈｏｙａ株式会社 | Optical information recording / reproducing device |
| US7843792B2 (en) | 2006-06-21 | 2010-11-30 | Hoya Corporation | Optical information recording /reproducing device and objective lens for the same |
| US7778139B2 (en) | 2006-10-17 | 2010-08-17 | Hoya Corporation | Optical information recording/reproducing device and objective lens for the same |
| US20080130465A1 (en) | 2006-12-04 | 2008-06-05 | Pentax Corporation | Objective Optical System and Optical Information Recording/Reproducing Device Having the Same |
| US8089705B2 (en) | 2007-04-23 | 2012-01-03 | Hoya Corporation | Objective lens for optical pick-up |
-
2007
- 2007-12-12 JP JP2007320829A patent/JP5199655B2/en not_active Expired - Fee Related
-
2008
- 2008-12-09 US US12/330,861 patent/US8279738B2/en not_active Expired - Fee Related
- 2008-12-10 CN CN200810185762.8A patent/CN101458940B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1571039A (en) * | 2003-04-25 | 2005-01-26 | 宾得株式会社 | Optical system of optical pick-up |
| CN1896773A (en) * | 2005-07-12 | 2007-01-17 | 宾得株式会社 | Optical disc drive and objective lens for the same |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101458940A (en) | 2009-06-17 |
| US8279738B2 (en) | 2012-10-02 |
| US20090154325A1 (en) | 2009-06-18 |
| JP5199655B2 (en) | 2013-05-15 |
| JP2009146484A (en) | 2009-07-02 |
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